The present invention relates generally to explosive shaped charges and, in an embodiment described herein, more particularly provides an oilwell perforator having a liner and/or case molded from a metal loaded polymer matrix.
Perforators are shaped charges specially configured for use in forming perforations extending from a wellbore and into a subterranean formation or zone. In general, perforators are specially configured to form either large diameter or deep perforations. Some perforators may achieve both, or neither, of these objectives. Furthermore, perforators have other goals, for example, reducing the amount of debris left in perforations and in wellbore by the perforators after they have been detonated, etc.
Perforators designed specifically to form large diameter perforations are typically made of a die stamped or deep drawn metal liner, and a machined steel or die cast zinc metal case. Perforators designed specifically to form deep perforations typically have liners made of die pressed and green or partially sintered metal powder. The cases are likewise machined steel or die cast zinc. Each of these has its disadvantages. For example, the deep drawing and die stamping processes are typically limited to producing liners with substantially constant wall thickness, the processes of die pressing and sintering metal powders, machining cases from steel barstock and die casting zinc cases are relatively expensive and/or time-consuming, especially when the cases have complex configurations, and zinc cases are reactive upon detonation and cause more damage to a perforating gun carrier than when steel cases are used.
Therefore, it may be clearly seen that a need exists for a perforator with enhanced manufacturability in terms of its economy and/or convenience, and which economically permits the use of complex shapes, for example, to refine the performance of the perforator. Such a perforator may also be useful in reducing damage to perforating gun housings and other downhole equipment, such as packers and pressure gauges.
In carrying out the principles of the present invention, in accordance with an embodiment thereof, an oilwell perforator is provided which includes a molding as the case and/or liner thereof. Associated methods are also provided. The perforator has enhanced manufacturability, the ability to assume relatively complex shapes, and is useful in reducing damage to perforating gun housings and other downhole equipment, such as packers and pressure gauges.
In one aspect of the present invention, the molding has a polymer matrix that is loaded with metal. The metal may be in powder form and may include one or a combination of copper, tungsten, lead, molybdenum, tantalum, iron, nickel, zinc, aluminum, or other metals. The molding may have a metal content of from approximately 20% to approximately 95% by weight.
In another aspect of the present invention, the polymer matrix m a y be any of a wide variety of polymer materials, including fluorocarbons, polybutadienes, polymides, nylons, phenolics, polyesters, polyphenylene sulfide, polyether sulfone, etc.
These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of a representative embodiment of the invention hereinbelow and the accompanying drawings.